This feature allows ftmod_libpri to ignore calls with non-matching destination number.

You may want to use this on BRI PTMP lines (Point-to-MultiPoint),
to avoid conflicts between your FreeSWITCH server and other devices connected to the line.

The filter is disabled by default (all calls will be accepted),
setting one (or more) "local-number" parameters on the span configuration enables it.

Example configuration snippet:

   <libpri_spans>
      <span name="example01">
         <!-- ... other span settings omitted ... -->
         <param name="local-number" value="123456"/>
         <param name="local-number" value="654321"/>
      </span>
   </libpri_spans>
Signed-off-by: Stefan Knoblich <stkn@openisdn.net>